We checked about 2 weeks ago. Ulster bank tracker was the cheapest if the amount borrowed was less than 60% of the value of the house. Also, as someone else posted, Ulster bank do not charge/or have a set charge for changing mortgage. Otherwise solicitor fees will set you back about a grand. Prima Finance also have a "remortgage" fixed rate fee for refinancing which is very good.

Bank of Scotland have a good deal on their tracker rate. Never more that 1% above the ECB with a 0.55% discount for 2 years. This equates to 2.7% for the next 2 years. They pay about €1k for legal fees as long as you don't move mortgages for 5 years.
You can also revert to an interest only for a period of time if you need cash for something else.
thegills